Khan Academy
The Khan Academy offers over 3,000 instructional videos covering everything from basic algebra to advanced chemistry, biology, and even the current day banking crisis. While working at an investment fund, Salman Khan started tutoring his younger cousins in his spare time by creating and posting videos to YouTube. As the videos grew in popularity, the Khan Academy was born. 3.5 millions learners use the site each month, and all videos are licensed under CC BY-NC-SA, with some already translated into Spanish, Arabic, Mandarin, Hindi, and more. The Khan Academy is currently exploring a system that awards learners points and badges as they progress.

Open Courseware
MIT OpenCourseWare has been releasing its materials — web versions of virtually all MIT course content — under a CC BY-NC-SA license since 2004. Today, MIT OCW has 2000 courses available freely and openly online for anyone, anywhere to adapt, translate, and redistribute. MIT OCW have been translated into at least 10 languages, including Spanish, Portuguese, Chinese, French, German, Vietnamese, and Ukrainian. In 2011, MIT OCW celebrated its 10th anniversary, having reached 100 million individuals, and announced MITx, an initiative to provide certification for completion of its courses. The OpenCourseWare concept has now spread to hundreds of universities worldwide.

CK-12 Foundation
The CK-12 Foundation addresses the growing costs of textbooks and the closed, outdated medium in which they are available. Focusing specifically on textbooks for U.S. K-12 schools, the nonprofit works with states and institutions to build web-based, collaborative “flexbooks” that are free to use and adapt in multiple formats like PDF, iPad and Kindle. Over 90 textbooks are available for reuse under the CC BY-NC-SA license. The CK-12 Foundation is also a major contributor to the California Free Digital Textbooks Initiative, a CA initiative that aligns open textbooks to state standards.

Connexions
Connexions is a repository and collaborative platform of educational materials that breaks down larger collections, such as textbooks and courses, into basic building blocks known as modules. Each module has a corresponding web page, so educators can mix and match pages to create custom lessons. All ~20,000 modules are licensed CC BY so they can be continually edited, translated, and adapted. Collaborative Statistics is an example of one textbook that has seen this remix and revision since its initial publication on the platform